Safety switch



Jan. 10, 1933. A. 3. VON NORMANN SAFETY SWITCH Filed June 12, 1931 2SheetsSheet R O T N E V m BY I fi/fmd 6 Von/7012mm Jan. 10, 1933. VQNNORMANN 1,894,074

SAFETY SWITCH Filed June 12, 1951 2 Sheets-Sheet 2 si 33 2a 0 23 3 28 2e20 l6 32 I my. 7 I 2 Z /5 2 2] 2O 10 3 w 3 I I [III I, I l3 ENVENTORATTORNEY Patented Jan. I 10, 1933 UNITED STATES PATENT OFFICE main) s.vox noammv, or smarts,

WASHINGTON, ASSIGNOB TO TBUHBULI;

ELECTRIC MANUFACTURING COMPANY, PACIFIC DIVISION, OF SEATTLE, WASH-INGTON, A CORPORATION OF WASHINGTON SAFETY Application filed June 12,

means for effecting a quick and snappy break between contacts of theswitch to thus reduce undesirable arcing when the switch is opened.

An important ob ect of the invention is to provide asafety switch ofthis nature having quick break means which is positioned on the exteriorofthe switch box or housing and lies parallel to said housing andoccupies a minimum amount of room and which makes possible the use of aswitch box or housing of less depth than it would be possible to use ifthe quick break mechanism were located within the box.

Another object is to provide a safety switch of this nature in which theswitch blades have a relatively long movement in propor tion to thedepth of the box and may be withdrawn into an open position asubstantial distance away from the clips with which they normally makecontact. I

Patent No. 1,687,835, issued to Andrew E.- Griswold on October 16, 1928,discloses a quick break safety switch in which the spring and otherparts of the quick break mechanism are disposed within the switch box orhousing. This necessitates a switch box of greater depth to provide roomfor said spring and quick break mechanism and to still afford room forample movement of the switch blades. In accordance with my invention Iplace the quick break spring and parts of the operating mechanism on theexterior of the housing and arrange them parallel to the front wall ofthe housing so that they will ,not take up a great deal of room on theexterior of housing and will allow a more shallow housing to be used.Another advantage of placing the spring on the exterior of the housingis that it precludes danger of short circuiting of the switch in theevent said sprlng should break. ther and more SP9? cific objects will beapparent from the 101- SWITCH m1. Serial in. 543,792.

lowing description taken in connection with the accompanying drawings.

In the drawings Figure 1 is a vertical midsection of a switchconstructed in accordance with my invention showing the switch closed.

Fig. 2, is a similar fragmentary sectional view showing the switch levermoved to the open position and the quick break spring compressed as itmight appear just prior to snapping the switch open.

Fig. 3 is a view similar to Fig. 2, showing 4 the switch open.

Figs. 4, 5 and 6 are detached perspwtive views of details of the quickbreak switch operating mechanism.

Fig. 7 is a cross section substantially on broken line 7 -7 of Fig. 1.

Fig. 8 is a detached perspective view of the switch bar.

Fig. 9 is a fragmentary exploded perspectlve View of parts of the switchbar.

Like reference numerals designate like parts throughout the severalviews.

Referring to the drawings, 10 designates a rectangular housing having aremovable front side 11 and having a panel 12 of insulating materialdisposed therein and secured to the bottom of said housing as by screws13.

Mounted on said panel 13 by screws 14 are a plurality of sets of s ringterminal clips 14 which are arranged or the reception of switch blades15, 16 and '17 said clips being constructed so that they frictionallygrip said blades when the switch is closed. Other terminal clips 18 andfuse plugs 19 may be provided in the usual manner on'the panel 12. Theswitch blades 15, 16 and 17 are each secured between plates 20 and 21 ofinsulating material as by rivets 22. Other plates 23 of insulatingmaterial of shorter length are disposed between the plates 20-21 andform a support against which the outer or rear edges of the switchblades rest. The ends of all of said plates which project beyond theswitch bars through a plate of' insulatin material 69 are slotted as at24 to from shaped heads 25 which are securely clamped within two channelshaped bars 26, said bars 26 being notched as at 27, Fig. 19 to receivewith their open sides together and are secured in assembled position byscrews 28 with the heads of the insulating blocks securely clampedwithin said bars.

Tubes 30 are also secured within the bars 26 and are slidably disposedon guide studs 31 which project upwardly from the bottom of the housing10 and which serve to guide the bars for opening and closing movement ofthe switch.

A switch operating link 32 is secured as by a clip member 33 to the bars26 and extends outwardly through a slot 64 in the front wall 11 of thehousing and through a slot 65 in a bracket 66 which is secured as byscrews 67 to the front wall of the housing. A thin plate 68 ofinsulating material fits loosely between the bracket 66 and housing wall11 and covers the slot 64. v

The outer end of the link 32 is positioned between the spaced apartupper ends of two plate members of similar construction which form alever member hereinafter referred to as a secondary lever 34. A pivot 36connects said plate members with the end of said lever. This pivot isremovably secured in place by a thin metal retaining member 36, Fig. 7,which is inserted between the plate members alongside of the end of linkand is bent over the head of the pivot 35. The plate members which formthe secondary lever 34 are bent as at 37 so that the lower ends of saidplate members lie flat against each other and these lower ends areinsertedbetween the spaced apart lower ends 38 of a two part switchoperating lever 39. A pivot member 40 extends through ears 41 on thebracket 66 and through the ends of the switch operating lever 39 andsecondary lever 34 thereby forming a common fulcrum for'said two levers.

The upper end of the secondary lever 34 is oifset relative to the lowerend thereof and is arranged to abut against and be stopped by the edgeof said switch operating lever when the two levers are in the relativeposition shown in Fig. 3. The two parts of the switch operating lever 39are spaced apart at their lower ends and are brought together towardtheir upper ends and secured to each other, preferably as by-spotwelding at 42, and are expanded or rounded above the said spot weld toform more convenient grasping means. An integral bell crank arm 43 onthe pivoted end of the switch operating lever 39 extends inwardly towardthe housing wall 11 and is provided on one edge with a spring engagingprojection 44 which extends in the same direction as the lever. Anotherspring engaging projection 45 is provided on the secondary lever 34 inopposed relation to the projection 44 and a'compression spring 46 as itsrespective ends fitted over said projections and is interposed betweenthe bell crank arm 43 and the secondary lever 34 so as to yieldinglyurge the secondary lever against the switch operating lever as shown inFigs. 1 and 3 but to compress and allow said two levers to be separated,as shown in Fig. 2, when the switch operating lever s first moved toopen the switch. Relative separating movement of the two levers 34 and39 is limited by engagement of the ends of the two projections 44 and45, which engagement may occur when the relative positions shown in Fig.2. Relative movement of said two levers in the op-' posite direction islimited by engagement of thespread apart upper end portions of thesecondary lever 34 with the adjacent edge of the lever 39.

In the operation of this safety switch when the levers 34 and 39 are inthe position shown in Fig. 1, the switch'will beclosed. the blades 15,16 and 17 will be frictionally held by the clips 14 and the levers willbe held in the upright position. To open the switch the operating lever39 is pulled outwardly into a position as shown in Fig. 2, the resultbeing that the spring 46 will first be compressed without moving theswitch blades but will snap the switch blades quickly into the openposition shown in Fig. 3, as soon as the pull on the link 32 overcomesthe frictional resistance exerted on the switch blades. If the spring 46is not strong enough to start initial movement of the blades saidmovement will be started by positive engagement of the ends of the twoprojections 44 and 45 and when movement is thus started the blades willbe quickly snapped into their open position by the spring 46.

The foregoingdescription and accompanying drawings clearly disclose apreferred embodiment of my invention but it will be understood that thisdisclosure is merely illustrative and that such changes may be made asare fairly within the scope and spirit of the appended claims.

I claim:

1. In a safety switch a housing, a switch panel within said housinghaving spring terminal clips thereon, a switch bar guided one endpivoted coaxial with said operating lever and the other end pivotallvconnected with the outer end of said link. said secondary lever and saidbell crank arm respectively having oppositely disposed spring receivingthe two levers are in projections thereon, and a compression spring onsaid projections between said bell crank arm and said secondary leverarranged to be compressed by opening movement of said operating leverwhereby said switch blades will be snapped into open position when thepull on said link overcomes the friction on said blades.

2. In a safety switch a housing, a switch panel within said housinghaving spring terminal clips thereon, a switch bar guided for movementtoward and away from said panel and having blades arranged to fit withinand be frictionally held by said terminal clips, a link connected withsaid switch bar and extending outwardly through a wall of said housing,an operating lever pivoted upon the exterior of said housing forswinging movement toward and away from the housing, said operating leverbeing substantially parallel to the housing when the switch is closed, ashort bell crank arm rigid with the pivoted end of said operating leverextending inwardly toward said housing, a secondary lever having one endpivoted coaxial with sald operating lever and the other end pivotallyconnected with the outer end of said link said secondary lever and saidbell crank arm respectively having oppositely disposed spring receivingprojections thereon, and a compression spring on said projectionsarranged to be compressed by opening movement of said operating leverwhereby said switch blades will be snapped into open position when the.pull on said link overcomes the friction on said blades, said twoprojections being arranged to abut against each other when the spring isfully compressed to insure the opening of the switch,

3. In a safety switch a housing, a switch panel within said housinghaving spring terminal clips thereon, a switch bar guided for movementtoward and away from said panel and having blades arranged to fit withinand be frictionally held by said terminal clips, a link connected withsaid switch bar and extending outwardly through a wall of said housing,an operating lever pivoted upon the exterior of said housing forswinging movement toward and away from the housing, said operating leverbeing substantially parallel to the housing when the switch is closedand being formed of two pieces spaced apart near their pivoted end, ashort bell crank arm on the pivoted end of said operating leverextending inwardly toward said housing, a secondary lever formed of twopieces spaced apart at one end for the reception therebetween of theouter end of said link said secondary lever having its other enddisposed between the two parts of said operating lever and pivoted onthe fulcrum of said operating lever, the spaced apart ends of saidoperating lever forming stop means engaging 'said operating lever, saidsecondary lever and said bell crank arm respectively having opp sitelydisposed springreceiv ng projections t ereon, and a compression springon said projections arranged to be com-- pressed by opening movement ofsaid lever whereby said switch blades will be snapped into open positionwhen the pull on said linkovercomes the friction on said blades.

4. In a safety switch a housing, a switch panel within said housinghaving spring terminal clips thereon, a switch bar guided for movementtoward and away from said panel and having blades arranged to fit withinand be frictionally held by said terminal clips, a link connected withsaid switch bar and extending outwardly through a wall of said housing,a bracket on the exterior of said housing an operating lever pivoted onsaid bracket for swinging movement toward and away from the housing,said operating lever being substantially parallel to the housing whenthe switch is closed, a short integral bell crank arm on the pivoted endof said operating lever extending inwardly toward said housing, andhaving a spring receiving projection thereon, a secondary lever havingone end mounted on the pivot of said operating lever and the other endpivotally connected with the outer end of said link, said secondarylever having a spring receiving projection thereon, and a compressionspring on said projection and disposed between said levers and saidhousing and arranged to be compressed by opening movement of saidoperating lever whereby said switch blades will be snapped into openposition when the pull on said link overcomes the friction on saidblades;

.5. In a safety switch, a switch bar embodying two channel membersdisposed with their open sides together, plates of insulating materialheld by said channel members and switch blades secured between saidplates of insulating material.

6. In a safety switch, a switch bar embodying two channel membersdisposed with their open sides together, said channel members havingnotches in their adjacent edges, plates of insulating material havingnotches extending from the edges inwardlv forming T shaped heads whichare held within said channel members and switch blades secured betweensaid plates of insulating material.

7. In a safety switch, a switch bar embodying two channel shaped membersdisposed with their open sides toward each other and rigidly securedtogether, said bars having sets of notches in their adjacent edges whichregister with each other, plates of insulating material notched to formT shaped heads which are held within and between said channel shapedmembers, the notched portions of said channel shaped members .and saidplates interfitting relative to each other, switch blades supported bysaid plates and an operating link connected with said switch bar on theopposite side from said switch blades. 7

8. The apparatus as claimed in claim 7 in which tubular ide members aresupported between said c annel shaped members and three plates ofinsulating material are provided for each switch blade, the blade beingheld flatwise between two of the plates and the edge of the bladeresting on the other plate.

The foregoing specification signed at Seattle, King County, Washington,this 3rd day of June, 1931.

i5 ALFRED G. VON NORMANN.

